1. Field of the Invention
The invention relates to a spray head for a spray device, which spray head is manually actuatable by pressing on an actuating element provided with an actuating surface against a pre-stretched spring, by means of which a sprayable, preferably liquid preparation in a container of the spray device can be sprayed out in atomized form, in a directed manner, by means of compressed air fed via an air-supply line from a motor-driven air pump as a source of compressed air, with a spray nozzle in which the compressed air fed to it, and the preparation fed to it via a riser tube, which had been separate from each other up to that point, are mixed, atomized and sprayed in a directed manner.
2. Description of Related Art
Spray devices which permit the spraying of liquids, e.g. pharmaceutical or cosmetic preparations, are known in a variety of designs. Here, as a rule, the liquid is sprayed out in a spray nozzle of the spray device in an atomized and directed manner by means of a stream of propellant gas.
Air, supplied via a hand pump (rubber ball pump) was originally used as the propellant gas. Later, special gases were used as propellant gases, in the product container itself or charged into a separate propellant gas container. However, recently--at least when fluorinated hydrocarbons are involved--their use has fallen out of favor, in order to prevent suspected environmental damage due to such propellant gases. The propellant gases more recently used as substitutes for fluorinated hydrocarbons are also objectionable, because they are sometimes flammable (propane) and during spraying, in combination with the oxygen of the surrounding air, they can explode with the formation of a flame jet, if they are inadvertently ignited by an open flame or an electrical spark. Other propellant gases used as substitutes (e.g. CO.sub.2) have the disadvantage that they must be charged into the container under very high pressure in order to assure that the entire contents of the container can be expelled in finely atomized form in the required manner. To make such highly pressure-resistant containers naturally requires an appropriately rugged and therefore costly manufacture of these containers. To an increasing extent, therefore, there has been a return to the use of hand pumps having a relatively simple construction, which supply ambient air as the propellant gas. It has been shown that the atomization and spray performance of such hand pumps, even though they are more advantageous from the environmental viewpoint, is relatively poor, because the supply of air that can be produced by actuation of the hand pump using (usually) one finger is very low, in terms of both the quantity of air as well as the air pressure, so that these hand pumps deliver only small quantities of spray, and the size of the droplets in the sprayed stream is also undesirably large in many cases.
Larger quantities of air at higher pressure can be supplied by external sources of compressed air of sufficient capacity, e.g. motor driven air pumps. This has recently led to the development of spray devices driven by compressed air, where the compressed air is supplied by pumps driven by electric motors. As long as these devices are used for the spraying of residue-free sprayable liquids, they can also be used advantageously owing to their satisfactory spray performance.
Problems arise if the liquids to be atomized or sprayed leave adherent solid or sticky residues, since such residues can deposit in the calibrated conduits, which are often very small, in the region of the spray nozzle. This rapidly impairs the spraying function, and after a short time nothing at all is expelled any longer, if the nozzle is not constantly cleaned. In addition, it is observed in such devices that small quantities of liquid continue to be delivered after use. These then dry within the conduits of the spray device and the spray nozzle, as well as on the outside of the spray nozzle; this likewise impairs the functioning of the device, even leading to total failure.